In many downflow type reactors that include a catalyst bed it is beneficial for the fluid feed to the reactor to be uniformly distributed across and through the catalyst bed. Often, to improve the fluid feed distribution across the catalyst bed, the reactor will be equipped with fluid distribution trays that provide for an improved dispersion of the fluid feed.
One example of a device providing for a uniform distribution of a fluid feed stream across a catalyst bed of a reactor is that which is disclosed in U.S. Pat. No. 5,403,561. This patent discloses the use within a reactor vessel of a flow distributor apparatus for uniformly distributing a mixed phase fluid stream across the top of a catalyst bed. The flow distribution apparatus includes a horizontal tray with a plurality of spaced apart chimneys extending through the horizontal trays. The lower end of each chimney has a spray means for producing a conical spray. The chimneys and spray means are positioned so that the spray patterns overlap and that none of the spray produced impinges on beams and other structural reactor internals located below the horizontal tray and above the catalyst bed. There is no other explicit disclosure of the use of support beams and other structure for supporting the horizontal tray nor is there a recognition of the problems associated with the inability to provide for fluid conduits for passing fluid from above the horizontal tray onto the catalyst bed at locations at which the horizontal trays are supported.
Another type of fluid distribution device is disclosed in U.S. Pat. No. 5,882,610 which is placed over a catalyst bed within a reactor and which provides for distribution of a gas-liquid mixture through a catalyst bed of the reactor. The distribution device includes a distributor plate having conduits such as orifices or mixing channels for passing fluid to the catalyst bed. This patent further teaches the support of the distributor plate by the use of stiffeners disposed upon the upper face of the distributor plate or by the use of support beams placed below the bottom of the distributor plate, or by both methods. The patent, however, fails to address or even recognize the problems caused by the placement of support beams below the surface of the distributor plate. Such problems occur when a distributor plate area is obstructed by support beams thereby rendering it not useable for the placement of fluid conduits or downcomers for passing fluid to the catalyst bed. This creates a void area over which no fluid is distributed resulting in a reduced uniformity in the fluid distribution across the catalyst bed.